Yeah I've heard this question and it's almost always from young ladies because they understand that they want to have children and there is the proverbial biological clock ticking. But the bigger issue is do I believe in the sovereignty of God? And the fact is is that God's plan for you is infinitely better than your own and His call to you at this moment is to be content today. Don't make the mistake of believing that you will be content if only circumstances A, B and C would fall into place, 'cause I guarantee you, you'll look back and you'll regret that you weren't content in the moment. And so don't worry about the number, whether you're 30, 31, 35 or 40, it doesn't matter. Just be content in the Lord and let Him work in your life, work hard for the Gospel and do those things that are pleasing to him and let Him worry about that part of your life.